--- title: "A Chart Is Worth Some Words" description: "Field notes on systems and sound, by Cory Watson." canonical: "https://onemogin.com/observability/charting/a-chart-is-worth-some-words.html" published: "2015-01-16T09:01:08.000Z" author: "Cory Watson" --- January 16, 2015 # A Chart Is Worth Some Words * * * [Remember when I told you about Loggerithim](http://onemogin.com/observability/tech/let-the-rithm-move-you.html)? Those were good times! Now we get to talk about the deep, dark rabbit hole I fell in after my work on Loggerithim ended. Charts were my number one frustration when working with Loggerithim. It’s hard to find a good charting library and it’s harder to build a system around charts when you can’t find a good library for it. At this time Javascript charting was shitty so dynamically generated charts were the thing to do. Digression: I remember when my dynamic charts were actually written to the filesystem in a temp directory and served and I had to use cron to clean it up. I was an idiot. Right, Charts! So I made my own! # Chart::Clicker Now you can see how [Chart::Clicker](https://metacpan.org/pod/Chart::Clicker) came to be. This library started out simple and become *insane*. I wrote a prodiguous amount of code to support a crazy idea and became a better programmer. # The Crazy Why do I keep saying that Clicker is crazy? Welp. The first reason is the name is nonsensical. I picked it because it sounded cool. The second and *real* reason it’s crazy is that [Stevan Little](https://twitter.com/stevanlittle) introduced me to [Moose](https://metacpan.org/pod/Moose) and listened to my crazy ideas long enough that I turned them into software. ![Loggerithim!](https://onemogin.com/assets/images/lr-crazy.png) # Intermediary Representations I decided that it would be cool if my chart wasn’t just a bag of shitty bytes but instead was an intermediary representation (IR) that could be transformed into a visual artifact. The idea was to generate a description of the chart — sort of like an [AST](http://en.wikipedia.org/wiki/Abstract_syntax_tree) in programming-land — and write drivers that converted that IR into whatever output you wanted. This was soooorta to serve a client need of embedding charts in PDFs. I’m proud to say it worked. But first I had to bring a bunch of shit to Perl-land. # Perl Shit First I needed some basic geometric facilities. I had spent lots of time as Java engineer and was spoiled by [Java 2D](http://docs.oracle.com/javase/tutorial/2d/). So I made [Geometry::Primitive](https://metacpan.org/pod/Geometry::Primitive). I needed to show you the geometry on the output side so I needed [Graphics::Color](https://metacpan.org/pod/Graphics::Color) to do that. With those two out of the way I could move up in the world and start thinking about actually creating my IR and [Graphics::Primtive](https://metacpan.org/pod/Graphics::Primitive) was born. Woe is me. Now I have a dilemma. If I’ve got this IR representing a chart and I need to draw it I’m gonna need some mechanism for layout. I somehow convinced myself that writing something akin to [Java’s Layout Managers](http://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html) was a good idea. So then I wrote [Layout::Manager](https://metacpan.org/pod/Layout::Manager). You should really go poke around in [the POD for Layout::Manager](https://metacpan.org/release/Layout-Manager). It’s crazy town. Somehow my wife — then girlfriend, if memory serves — didn’t break up with me even though I was constantly drawing on whiteboards and complaining about layout management for weeks. But in the end, fuckin’ el did it pay off! I ended up with an output agnostic IR that could be passed to drivers such as [Cairo](https://metacpan.org/pod/Graphics::Primitive::Driver::Cairo) to rasterize them. I also learned all about fun things like recursion — which I believe later led me to enjoy functional programming more and drew me to Scala — and the [painter’s algorithm](http://en.wikipedia.org/wiki/Painter%27s_algorithm). [Here’s a PDF version of a talk I gave at a Perl conference](https://onemogin.com/assets/talks/Data-Viz-w-ChartClicker.pdf) on Chart::Clicker. It was packed and I really felt like I’d done something people cared about. :) # Culmination In the end I went further into the weeds and wrote [Document::Writer](https://metacpan.org/release/Document-Writer) which carries this idea further and creates an IR for *page layout* for fuck’s sake. The incredible part about this, if I do say so myself, was that Document::Writer built on Graphics::Primitive and Clicker charts could be embedded directly *in the document* and rendered by an arbitrary backend. Fully vector PDFs with charts in ’em people. I even made a *better* driver and combined [Cairo](http://cairographics.org/) and [Pango](http://www.pango.org/) for the imaginatively named [Graphics::Primitive::Driver::CairoPango](https://metacpan.org/pod/Graphics::Primitive::Driver::CairoPango). Unfortunately I can’t find any examples of the output of this work. But it’s awesome. # So, Charting? Right, sorry. I love telling this story because it is important to me. Chart::Clicker was born because, damnit, I wanted there to be a good charting library. Unfortunately by the time I realized that huge amount of work, client-side charting had really come into it’s own. Client-side charts so significantly better in terms of interaction and presentation. Shucks. This time also was a golden era for me in terms of friendships, impact and becoming a real member of a technical community. It was a lot of fun. Feel free to [look at all the wonderful things](https://metacpan.org/pod/Chart::Clicker#Renderers) the library could render.